Try to keep constructor calls together. Fix #119.

lib/src/source_visitor.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart_style.src.source_visitor;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/generated/source.dart';
 
@@ skipping 801 matching lines @@
       token(node.period);
     } else {
       visit(node.target);
     }
     token(node.leftBracket);
     visit(node.index);
     token(node.rightBracket);
   }
 
   visitInstanceCreationExpression(InstanceCreationExpression node) {
+    _writer.startSpan();
     token(node.keyword);
     space();
     visit(node.constructorName);
     visit(node.argumentList);
+    _writer.endSpan();
   }
 
   visitIntegerLiteral(IntegerLiteral node) {
     token(node.literal);
   }
 
   visitInterpolationExpression(InterpolationExpression node) {
     token(node.leftBracket);
     visit(node.expression);
     token(node.rightBracket);
@@ skipping 838 matching lines @@
   /// Gets the 1-based line number that the beginning of [token] lies on.
   int _startLine(Token token) => _lineInfo.getLocation(token.offset).lineNumber;
 
   /// Gets the 1-based line number that the end of [token] lies on.
   int _endLine(Token token) => _lineInfo.getLocation(token.end).lineNumber;
 
   /// Gets the 1-based column number that the beginning of [token] lies on.
   int _startColumn(Token token) =>
       _lineInfo.getLocation(token.offset).columnNumber;
 }